release: 0.2.0, so that pip --upgrade actually delivers it

[adiazpar]

A user reported still having the old version after installing from the git URL. Reproduced
from a clean environment against the pre-refactor commit:

Command	Result
pip install git+…	no change
pip install --upgrade git+…	no change
pip install --force-reinstall git+…	works

Why

Not a pip bug. Installing from a git URL does not use tags — this repo has none. pip
clones the default branch, reads version out of pyproject.toml, and compares that single
string against what is installed. Every change since the first release went out under
0.1.0, so pip compared 0.1.0 to 0.1.0 and concluded there was nothing to do.

It had already cloned the new code and recorded the new commit id in direct_url.json. It
threw the clone away.

So the entire refactor — baseline-free authoring, the shipped palette, the flute-pitch fix —
was unreachable by the upgrade command the README tells people to run.

0.2.0 is also the honest number: --out is gone, author_sound_timeline's arguments
swapped, and the pytest marker was renamed.

What was never wrong

Replacement itself. Verified that pip uninstalls the old distribution first, so none of the
six modules from the old flat layout (palette.py, midi.py, gm.py, voices.py,
events.py, timeline.py) survive alongside the new subpackages. One dist-info, no
duplicates.

tests/test_packaging.py

New, and it had no counterpart. The version is declared twice — pyproject.toml and
__init__.py — and nothing connected them; a release where those disagree ships a package
that reports one number and upgrades on another.

It also pins the two packaging fields whose failure mode is silent and total:

• the explicit packages list — a forgotten subpackage installs fine and fails on import
• package-data — a missing entry drops the sound palette out of the wheel, and every
  compile raises on a machine that installed rather than cloned

README

Documents the upgrade command, why it did nothing, and the one-time --force-reinstall that
unsticks it — plus @ref for pinning a specific version.

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